Shallow Trench Isolation Fillet Structure for Reduced Point Discharge
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Solution Overview
Problem
Conventional shallow trench isolation structures face issues with point discharge and reliability, particularly due to sharp corners that can lead to electrical leakage and reduced isolation effectiveness in high-density semiconductor devices.
Innovation Solution
The implementation of a shallow trench isolation structure with a fillet curve edge corner between the substrate and trench inner walls, featuring sequentially stacked dielectric layers and a polysilicon layer, which reduces point discharge by creating a smooth, rounded edge, thereby enhancing the reliability of the isolation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional shallow trench isolation structure with sharp corners is used, then the manufacturing process is simple, but point discharge occurs and reliability is reduced
Solution Approach 1:
The patent applies curvature by forming a fillet curve at the edge corner between the substrate and the inner wall of the trench. This rounded geometry eliminates the sharp corner that causes point discharge, thereby improving isolation reliability while managing the additional processing steps required to create the curved profile.
2Reliability
If multiple dielectric layers are stacked to improve isolation effectiveness, then electrical insulation is enhanced, but device complexity increases
Solution Approach 1:
The patent implements local quality by using different dielectric materials in different regions and layers of the trench structure. The first, second, and third dielectric layers are sequentially stacked with different material properties optimized for their specific positions, providing enhanced electrical insulation where needed while managing overall structural complexity.
Solution Approach 2:
The patent employs composite materials by combining multiple dielectric layers with different properties within the same isolation structure. This multi-layer composite approach improves electrical insulation effectiveness and isolation performance while distributing the complexity across functional layers rather than requiring a single complex material.
3Reliability
If the trench edge corner is rounded with a fillet curve, then point discharge is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies curvature by forming a fillet curve at the edge corner between the substrate and the inner wall of the trench. This rounded geometry eliminates the sharp corner that causes point discharge, thereby improving isolation reliability while managing the additional processing steps required to create the curved profile.
Data Source
AI summary
A semiconductor device includes a substrate; at least one trench located at a top surface of the substrate; and a first dielectric layer, a second dielectric layer and a third dielectric layer that are sequentially stacked on an inner wall of each of the at least one trench. A topmost surface of the first dielectric layer is lower than a topmost surface of the second dielectric layer and the top surface of the substrate, to form a first groove between the second dielectric layer and the substrate. An edge corner between the top surface of the substrate and the inner wall of each of the at least one trench is in a shape of a fillet curve. The fillet structure is smooth and round without a sharp corner, reducing point discharge and improving reliability of the shallow trench isolation structure.